Tuesday, June 26, 2012

Mary
and I observed both painted and snapping turtles laying eggs as of June 7th,
which seems a week or so early for our area.

Here’s a quick
snapshot of the spring-to-fall lifecycle of a snapper:

Snapping
turtles in our latitude typically emerge from hibernation in early May when the
water is about 41 to 50° F. They initially bask while moving around some, but
don’t eat until the water reaches about 60° F. The females soon undertake
nesting migrations in search for a preferably sandy, sunny nest site.
Interestingly, the males also migrate and aggregate in areas close to major
nesting sites and on migration bottlenecks in order to intercept the females
and mate. Ideally, the females will locate their nests close to small streams,
where the hatchlings will then spend their first couple of years before they
move into larger bodies of water.

Females may
migrate long distances, 2 to 8 miles through lakes and rivers, to find ideal
spots. By turtle standards, the migrating individuals often move relatively
fast – the mean speed of travel can be up to 1 mile per day.

When the
female reaches her desired site, she digs a nest chamber, a task that will take
her about an hour and a half, and then she will lay from 22 to 62 one-inch
diameter eggs. Once her eggs are laid, she will fill the nest hole again with
sand, press it down, try to camouflage the nest, and leave. Unfortunately, up
to 90% of the nests will be destroyed by predators like raccoons, skunks,
foxes, and mink, often almost immediately.

The eggs hatch after 60 to 120 days,
usually in September in this area. Cold temperatures in our area constrain
embryonic development. Snappers have temperature dependent sex determination,
which means that the sex of the turtle depends on the temperature at which the
egg was incubated – males like it colder, females warmer.

The hatchlings
will dig out of the nest and somehow know to head straight for the nearest
water, even if they cannot see it. If the weather is too cold after hatching,
the hatchlings may sometimes try to overwinter in the nest.

Today’s
snapping turtles have hardly changed from 215 million years ago when the most
primitive turtles lived. In comparison,
the age of the dinosaurs was approximately 150 million years ago, 65 million
years later than the first turtles. To put things into further proportion:
humans are estimated to have evolved a mere 3.5 million years ago.

Abundance of Butterflies and Moths

Numerous people have told me they are seeing
unusually high numbers of butterflies and moths, and have wondered why. I asked
Phil Pellitteri at the UW Madison Insect Diagnostic Lab for his interpretation,
and his very short and straightforward reply was this: “Lots blew in from down
south with all the strong southerly winds. Mild winter helped our natives. Dry
weather is good for caterpillars.”

6/7: Mary and I
saw a pair of trumpeter swans with 6 chicks on the Little Turtle Flowage near
Mercer.

6/7: Hannah Dana wrote: “My cousin, Dr. Tom
Petersen and his wife, Sharon, live on Mercer Lake. A couple of weeks ago they
were looking out the window overlooking the lake shore and saw a mother Canada
goose with her brood. They noticed that the last gosling in the queue was
stumbling and lagging behind. Then they realized something was wrong, and Tom
went to the lakeshore to see what was going on. The little one was wrapped
in gobs of fishing line that some idiot had thrown in the water rather than
keep in the boat to dispose of later. The mother and the siblings swam farther
around the bay and didn't seem to realize the last in line was in
trouble. Tom picked up the gosling and took it into the house. Tom, a
dentist, used tweezers to lift the knots and Sharon, a nurse, used a tiny
scissors to cut the line. Finally, the baby (who had remained calm) was
free of its imprisonment, and Tom returned it to the water. Lo and behold,
Mom and the crew turned around and swam back to it, encircled it and murmured
as if to say, "Welcome back. Are you okay? What was it like in that
People House?" Then, they went on their way around the point to the next
bay.

“Years ago, I would visit my
friend, Marge Gibson, who runs the Raptor Education Center in Antigo. So many
eagles, loons, swans and other creatures would be ensnared by line discarded by
fishermen. She was able to save many of them, but some died from
starvation, drowning, dehydration etc. I find no excuse for
"sportsmen" being too lazy to take their old line home, preferring to
throw it into the water. Surely, they must be able to foresee what could
happen to the birds and animals that get caught up in it.”

As
a related note, in a current study of 10 loon nests on the Turtle-Flambeau
Flowage, nearly all the eggs were laid from May 10 to 17. Since loons employ a
28-day incubation period, those eggs that weren’t predated or flooded out
nearly all hatched in the window from June 10 to 17, as should be the general
case for loon nests throughout our area.

6/12: Pat Schwai
on Cochran Lake wrote: “When I was a child, my family camped at Twin Lakes
campground in Price County, just a short distance from our present home.
The call of the whip-poor-wills was a nightly event. But since arriving
here in 1996, we've seldom heard them, and then only at a distance. This
year we heard our first whip-poor-will on May 30. It has progressively been
calling closer to our house, which is not quite as delightful at 4 a.m.
Nevertheless, we feel very fortunate to hear him nearly every evening because
whip-poor-wills seem to be rare. Are they?”

I
wouldn’t say rare, but whip-poor-wills are certainly uncommon. Breeding birds
appear to strongly prefer very open, dry woodlands since most of their feeding
is done in open spaces at night. In areas where brush has grown up in the
understory, where moths have declined due to the use of pesticides, and where
predators like raccoons have increased, whip-poor-wills have correspondingly
decreased.

6/14: Pete Dring
observed large leaf aster in bloom, which is extremely early for this plant to
be flowering – it usually blooms around mid-July.

Celestial Events – Summer Solstice

Summer
solstice is widely recognized as the beginning of summer in the Northern Hemisphere
and the beginning of winter in the Southern Hemisphere. The
solstice represents a “turning” of the year – the sun is now rising and setting
as far north as it ever does.

However,
for people living around 40° north
latitude, the latest sunsets of
the year happen in late June (at our latitude of 46°, the latest sunset of the
year comes on or near July 1 every year). And conversely, in the Southern
Hemisphere at 40°south latitude, it’s the year’s latest sunrises that happen around this time of year despite the
fact that the longest (or shortest) day of the year falls on the June 20
solstice.

Several
weeks ago when Mary and I were hiking in far northwestern Scotland in an area around
58° latitude, it seemed like it never got dark. We’d go to bed around 11 p.m.
and though we’d get up now and again during the night, we never were up at a
time when it was actually fully dark.

For
perspective, we live in Manitowish at about 46.1° north latitude. Each degree
of latitude represents 69 miles further north, so at our cottage in Poolewe, Scotland,
we were over 800 miles north of Manitowish. For comparison sake, head 800 miles
north from the Lakeland area and you’ll find yourself in uninhabited, roadless
areas of northern Ontario, or further east, you’d be swimming in the middle of Hudson’s
Bay.

People
can, however, live just fine in far northwestern Scotland, because the Gulf
Stream brings warm ocean water along the coast which moderates the climate.
Because of those warm Atlantic currents from the Caribbean, the coldest winter
temperature ever measured in Poolewe was 14°F in 1986, while temperatures are
rarely very hot in summer; the highest temperature recorded was 84°F in June
1978.

The
Gulf Stream is such a remarkable moderating factor that in Poolewe you can
visit Inverewe Gardens, a 50-acre, world-renowned garden that is an oasis of
exotic plants – rhododendrons from the Himalayas, eucalypts from Tasmania,
olearia from New Zealand, and other species from such far-flung places as Chile
and South Africa.

The
garden was created in 1862 by Osgood Mackenzie
on a 850 hectares (2,100 acres) estate bought for him by his mother. When he
placed rabbit and deer fencing around the headland in Loch Ewe in 1862, there
was just one tree, a three-foot-high dwarf willow, within the boundaries he had
selected. Since the west coast of Scotland is susceptible to strong winds and
salt spray, one of the first things Osgood did was establish shelterbelts of
pines. He reclaimed the seashore with good soil reputed to have been brought by
the basketful from Ireland, and by the end of the century he had established
one of the finest collections in Scotland of temperate plants from both
Northern and Southern hemispheres.

Which
all just goes to show what determination, imagination, and no small amount of money
can achieve. And as a result, visitor numbers now approach 100,000 per year.

Fireworks and Birds

As
July 4th approaches, I’m obliged to simply remind folks that many
birds are still nesting or are raising their young. Since fireworks and nesting
birds don’t coexist well, please consider which you prefer more.

Mary
and I just returned late last night (6/4) from two weeks of hiking in the highlands
of northwestern Scotland, and though our legs be a wee bit tired, we had a
glorious time. I apologize for not responding to those of you who e-mailed and
called over this time with many interesting sightings, and for not reporting
those sightings in this week’s column. I promise to write them all up in my
next column.

As
for what natural history connections exist between northern Wisconsin and
northern Scotland, so much overlaps that it’s hard to know where to begin! It’s
always fascinating to see non-native, invasive species in Wisconsin that are no
problem in their native land. Mute swans, starlings, and house sparrows come to
mind right away, and it’s notable that several of them are in decline in
Britain. Starlings have been declining sharply in Britain for many years, in
part due to changes in agricultural practices and the loss of permanent
pasture. Our “RSPB [Royal Society for the Protection of Birds] Handbook of
Scottish Birds” actually suggests “these birds can be helped by the provision
of nestboxes,” a suggestion that would horrify North American birders.

House
sparrows, too, have declined – a 62% loss in Britain between 1974 and 1999, a
decline that continues to this day and is somewhat of a mystery.

Mute
swans, however, are doing fine. They number 1,000 pairs in Scotland alone, and
have recently been expanding their range largely due to a ban on the sale of
lead fishing weights and the prohibition of lead shot in cartridges used over
wetlands. The swans were once prized for food at banquets, and I suspect their
failure to appear today on local menus has also improved population growth.

Red Squirrels – An Endangered Species in
Scotland

Invasive
species cross the ocean both directions, of course. Our North American grey
squirrel was introduced into Britain in the late 19th
century (1876 onwards), and has replaced Britain’s native red squirrel in most
of its former range.

Three factors
have led to the profound decline of red squirrels. Red and grey squirrels
occupy a similar ecological niche. Both are small tree-dwelling mammals that
rely on similar food sources (tree seeds, nuts, berries, etc), but because of
differences in their ability to digest large seeds and acorns from broadleaved
trees, grey squirrels have a competitive advantage over red squirrels that
results in weight loss and reduced breeding success for reds.

Extensive tree
cutting between 1914 and 1945 throughout Britain, and subsequent felling of
Scots pine and Norway spruce plantations as they mature, have largely been
replaced with new plantations of Sitka spruce that offer a limited food supply
for red squirrels. Remaining woodlands have been further fragmented by the loss
of an estimated 50% of the hedgerow habitat in Scotland between the 1940s and
1980s. Continuity of habitat is important, and the loss of hedgerow links
between woodlands has resulted in the isolation of red squirrel populations,
increasing the risk of losses from predation when red squirrels have to cross
open areas.

But the most
devastating reason for the decline of red squirrels has been the incursion of
the Squirrelpox virus, carried by gray squirrels. Harmless to them, it’s lethal
to the native reds, with the reds dying a horrible death over two weeks. The
Squirrelpox virus also has the devastating effect of speeding up the rate at
which grey squirrels displace and replace reds (usually about 15 years) by a
factor of twenty, denying researchers adequate time to develop an effective
vaccine for reds.

Scotland is
home to over 75% of Britain’s endangered red squirrels with the country
representing one of the last strongholds for the species in the UK. We saw
numerous red squirrel road-crossing signs throughout Scotland, and a very
concerted effort has been undertaken to vastly reduce the grey squirrel
population.

Scotland’s red
squirrel is a bit different than Wisconsin’s, most notably in having pointed
ear tufts, but otherwise looks and acts the same. How interesting that a
species that is considered so common to us is of such great concern to people
in Britain.

Other Invasive North American Species - Mink and Ruddy Duck

Ruddy
ducks became established in Britain and Europe after escaping from wildfowl
collections. In Spain, ruddies hybridize with an endangered species of
white-headed ducks, but because ruddies are a dominating species, the fear is
that they will exterminate the white-headed duck from all of Western Europe.
Thus, a major cull of ruddy ducks is currently being carried out by many
countries across Europe.

As
for American minks, Scotland has been overrun by them. The animals were brought
to Britain back in the 1950s to be farmed for fur coats, and now tens of
thousands are running wild and wreaking havoc on other species.

The minks
patrol river and loch banks looking for birds and frogs and small mammals — in
particular voles. Voles are beloved in Scotland, famed by Scottish novelist
Kenneth Grahame who used a water vole as a main character in his children's
book TheWind in the Willows.

Now, 95% of
the voles are gone, thanks in large part to the minks. The Scots have
a major campaign to clear their lands of the invaders, with the goal to kill
them all! So far, nearly 4,000 square miles of Scotland have been declared
mink-free.

Osprey Reestablishment

And
then there are those species that are circumpolar in their distribution, some
of which are doing very well here, but are struggling there. Ospreys are
particularly notable. The osprey used to be
distributed throughout Europe, but heavy persecution, mainly by Victorian egg
and skin collectors during the 19th and early 20th century, brought about
dramatic decreases and extinctions.

The osprey
became extinct as a breeding bird in England in 1840 and in Scotland in 1916.
In 1954, it recolonized naturally and a pair has nested successfully almost
every year since 1959 at Loch Garten, an RSPB reserve in Scotland’s Cairngorms
National Park. The Osprey Centre at Loch Garten has become one of the most
famous conservation sites in the world –
over 2 million people have visited to see a particularly famous pair of nesting
ospreys, the 27-year-old female of which has now returned for 22 consecutive
years to breed, and has successfully reared 50 chicks. She winters
roughly 6,000 miles south in West Africa.

The osprey’s
overall reestablishment was very slow, probably because of organochlorine
pesticides in the food chain and due to the continued activities of egg
collectors, and had reached only 14 pairs by 1976. However, by 2001, 158
breeding pairs were located, mainly in Scotland. That same year saw the first
successful nesting of ospreys in England.

Ospreys now number around 200 pairs in Scotland,
and we saw one nest on top of an electric pole, just like around here, on a
trail at the Pass of Killiecrankie not too far from Loch Garten.

Handa Island Seabirds

Perhaps
the birding highlight of our trip was a visit to Handa Island nature reserve near
the tip of northwestern Scotland. Managed by the
Scottish Wildlife Trust (SWT) Handa’s dramatic sea cliffs host one of the
largest seabird breeding colonies in Europe with around 100,000 breeding birds,
including internationally important numbers of guillemots and razorbills.

From the cliff
path, we could observe the nesting bird's daily activities. Around 45,000
guillemots nest precariously on narrow cliff ledges, along with thousands of
kittiwakes, fulmars, razorbills, and a small number of puffins that breed in
burrows lining the cliff edges.

Great skuas
and Arctic skuas nested on the ground across the moorland areas of the island, along
with red grouse and common snipe on the island, all of which were remarkably
approachable because of no hunting on the island. We were able to watch a red
grouse displaying for a female who paid him little attention, instead
continually bathing herself in dirt. Arctic tern colonies have also recently
formed on the southern shores and we could see them feeding in the shallows of
the landing beach.

Back in the U.S. – Great Backyard Bird
Count

Participation
in the 15th Great Backyard Bird Count, February 17-20, shattered all previous
records. Bird watchers in the U.S. and Canada submitted more than 104,000
checklists, reported 623 species, and observed more than 17.4 million birds.
New checklist records were set in 22 states and in 6 Canadian provinces.

Participants reported the northern
cardinal on more checklists than any other species for the eighth year in a
row, closely followed by the mourning dove. The most numerous bird species
reported during this year’s count was the snow goose, followed by the tree swallow,
with its first-ever top-10 appearance. A single massive flock of an estimated
one million tree swallows was reported in Ruskin, Florida (Google this event to see videos)!

This year’s
GBBC results are available on the website (http://www.birdsource.org/gbbc/).
GBBC maps show reports for snowy owls that plainly demonstrate the massive
influx compared to previous years. The maps also show that common redpolls moved
farther south in western areas in search of food, while a lack of acorns may have
reduced reported numbers of blue jays in the Northeast. Sandhill cranes and
red-winged blackbirds were also found to be already migrating during the count.

Thursday, June 7, 2012

I
think we say this every spring, but the ticks seem – how shall I say this
– abundant! Our dog had at least
50 on her after a hike in the Harrison Hills on 5/5. After you handle that
many, every itch you have feels like a possible tick!

“Know
thy enemy” said the ancient Chinese general Sun Tzu, so here’s what
seems to me to be important to know:

Since deer
ticks (Ixodes scapularis) are the ones that transmit Lyme disease, let’s focus on them. Deer
ticks live two to three years and have three blood meals. The life cycle
begins when the female lays upwards of 2,000 eggs, which hatch anywhere from
May to September. Each individual larva is the size of a period at the end of a
sentence, and initially does not carry Lyme disease. However, it may pick up
diseases during its first meal if the host, usually a white-footed mouse or
other small mammal, is infected. The larva then becomes infected and can
transmit these organisms during its second or third feeding the following
years. However, if the tick feeds on an uninfected small mammal or bird, these ticks
cannot transmit disease.

After
this first feeding, the larvae molt into nymphs and become dormant until the
following spring. In the spring and summer of the tick’s second year, primarily
from May through early July, the
nymph becomes active and takes its second feeding from a mammal. If the tick is
carrying disease agents from its first feeding in the larval stage, it can
transmit them during this second feeding. If the nymph was not infected
the previous year, it can become infected now if the second meal host is
carrying disease agents.

The
nymph is about the size of a poppy seed. Nymph stage ticks often look like a
speck of dirt or a freckle on a person’s skin.

In
the fall of the second year, the nymphs then molt into adult ticks. Adults are reddish-brown and about 1/8-inch long (or about one-half the
size of the more familiar female wood tick). The female is larger than the
male, and though the male ticks may attach, they
do not feed or become engorged.

The
adult female then feeds on large animals, primarily on deer, and then lays eggs the following spring. If the female
doesn’t get a blood meal by the end of the fall, she goes dormant over the winter
and seeks a meal in the spring. A frost does not kill deer ticks. Adults
may become active as soon as it is above freezing and may even be spotted
during a temporary thaw in the winter.

Deer ticks (and
wood ticks) wait for host animals from the tips of grasses and shrubs (not from
trees). When brushed by a moving animal or person, they quickly let go of the
vegetation and climb onto the host. Ticks can only crawl; they cannot fly or
jump.

Deer ticks are dependent on the white-tailed deer population for reproduction.
Larval and nymph stages feed on birds and small mammals, but the adult female
tick needs a large 3-day blood meal, usually from a deer, before she can
reproduce and lay her eggs. Deer are the primary host for the adult deer tick
and are key to the reproductive success of the tick.

Numerous
studies have shown that abundance and distribution of deer ticks are correlated
with deer densities. For example, when the deer population was reduced by 74%
at a 248-acre study site in Connecticut, the
number of nymphal ticks collected at the site decreased by 92%.

The
relationship between deer abundance, tick abundance, and human cases of Lyme
disease was also well documented in Mumford Cove near Groton,
Connecticut.

From 1996 to 2004, the deer population in
Mumford Cove was reduced from about 77 deer per square mile to about 10 deer
per square mile after focused hunting, which was enough to reduce by more than
90% the risk of humans contracting Lyme disease.

Remember: if a deer tick is infected, it must be attached for 24 to 48
hours before it transmits Lyme disease. The best defense is to check
yourself for ticks thoroughly every morning and night.

Relatively Quiet Birding

Mary and I led two bird hikes on 5/12 and 5/13
in the Lakeland area, and I co-led two other bird hikes on 5/18 and 5/19 on the
Apostle Islands. The birding was rather slow, a surprise given that mid-May is
THE time for seeing maximum numbers of songbirds. Many warblers appear to be
heading straight for their nesting territories. Bird researchers are finding
warblers back on territory a little ahead of schedule, likely due to the
advanced leaf out. Weather patterns have also not been conducive to large migratory
movements. Much of the month has been dominated by high pressure. There have
been few of the good Gulf of Mexico lows that come in from the south or
southwest and bring a major wave of migrants.

Still, during the Chequamegon Bay Birding and
Nature Festival on 5/17,
Ryan Brady reported 22 species of warblers at Bark Point (west of
Cornucopia) on Lake Superior, including close-up looks at a singing Connecticut
warbler, a species often very difficult to find. He noted that there were not a
lot of individuals, but lots of diversity.

The total tally for the event reached 176
species, around the average number they have found in previous years. Because
Chequamegon Bay offers such an amazingly diverse range of habitats – from open
farmlands to small towns to vast wetlands to the Apostle Islands – their
festival tends to record many more species than we do at our local festival in
Manitowish Waters. For instance, on one hike on 5/19, they found 17 species of
shorebirds – we just don’t have shorebird habitat at all comparable to Lake
Superior, though we did see long-billed dowitchers at the Little Turtle Flowage
on 5/13 (see the photograph by Juan Fernandez). The Chequamegon event also runs
over 100 activities across three days, so there are a lot more eyes and ears
out there counting birds.

Still, bird festivals really aren’t about
seeing maximum numbers of birds. They’re more about the joy of being in
beautiful places, feeling connected to the natural world, and sharing that
pleasure with other like-hearted people – the birds are just part of the total
experience.

5/11: Bob
Bridges on Papoose Lake near Boulder Junction observed a red-headed woodpecker
being chased by a yellow-bellied sapsucker.

5/11: Louise
Church also spotted a redhead woodpecker in Hazelhurst.

5/12: Judith Bloom on Lake Tomahawk reported her first-of-year
indigo bunting. She also checked the loons on Lake Tomahawk, and found the nests of
five of the six pairs. All five are on nest, and Judith noted that this was
early and hopefully means that the black flies will not bother them this
year. Last year only one chick fledged on Lake Tom – the average is
five. Judith asked that I remind everyone to please stay 200 feet away
from any loons and their nests, and to obey “slow no wake” signs everywhere as
nests can be where you least expect them.

5/13: Mary
Henkel in Harshaw reported a pair of orchard orioles – a rare species in our
area – as well as two pairs of Baltimore orioles, visiting feeders at their
home on Little Bearskin Lake.

5/13: Peter and
Carolyn Dring reported Jack-in-the-pulpit and nodding trillium first in bloom
in the Land O’Lakes area.

5/17: In Mercer, a fawn and doe were
sighted walking across a pasture, a relatively early date for the appearance of
fawns.

5/21: Mary and I saw our first bobolink on Powell
Marsh.

Celestial Events

For planet-watching in June, look after
sunset for Mars and Saturn, both in the southwest, and Mercury low in the
northwest. Before dawn, look for Venus low in the northeast by mid-month and
Jupiter also very low in the northeast.

June
1 offers us 15 hours and 30 minutes of daylight – fabulous!

Look
for the full moon – the “Strawberry” or “Rose” moon – on 6/4. A partial lunar
eclipse will occur that night, though in Wisconsin the moon will set well
before mid-eclipse. We will observe a deepening shadow creeping left to right
across the lower portion of the moon. The eclipse begins at 3:38 a.m., and the
moon will set at 5:18 a.m.

On
6/5, Venus will transit across the face of the sun, an event that won’t occur
again until 2117, which I doubt too many of us will be around for! Called “The
Black Drop,” Venus will sail across the sun for over three hours, creating a
visible small black notch in the sun. The transit begins at 5:04 p.m. and
continues until sunset at 8:45, only partially making its way across the sun
before it sets.

Viewing
the transit through binoculars will enhance the event for you, but to protect
your eyes you must use proper filters such as an
astronomical solar filter, eclipse viewing glasses, or Grade 14 welder’s glass.

Mary
and I just returned late last night (6/4) from two weeks of hiking in the highlands
of northwestern Scotland, and though our legs be a wee bit tired, we had a
glorious time. I apologize for not responding to those of you who e-mailed and
called over this time with many interesting sightings, and for not reporting
those sightings in this week’s column. I promise to write them all up in my
next column.

As
for what natural history connections exist between northern Wisconsin and
northern Scotland, so much overlaps that it’s hard to know where to begin! It’s
always fascinating to see non-native, invasive species in Wisconsin that are no
problem in their native land. Mute swans, starlings, and house sparrows come to
mind right away, and it’s notable that several of them are in decline in
Britain. Starlings have been declining sharply in Britain for many years, in
part due to changes in agricultural practices and the loss of permanent
pasture. Our “RSPB [Royal Society for the Protection of Birds] Handbook of
Scottish Birds” actually suggests “these birds can be helped by the provision
of nestboxes,” a suggestion that would horrify North American birders.

House
sparrows, too, have declined – a 62% loss in Britain between 1974 and 1999, a
decline that continues to this day and is somewhat of a mystery.

Mute
swans, however, are doing fine. They number 1,000 pairs in Scotland alone, and
have recently been expanding their range largely due to a ban on the sale of
lead fishing weights and the prohibition of lead shot in cartridges used over
wetlands. The swans were once prized for food at banquets, and I suspect their
failure to appear today on local menus has also improved population growth.

Red Squirrels – An Endangered Species in
Scotland

Invasive
species cross the ocean both directions, of course. Our North American grey
squirrel was introduced into Britain in the late 19th
century (1876 onwards), and has replaced Britain’s native red squirrel in most
of its former range.

Three factors
have led to the profound decline of red squirrels. Red and grey squirrels
occupy a similar ecological niche. Both are small tree-dwelling mammals that
rely on similar food sources (tree seeds, nuts, berries, etc), but because of
differences in their ability to digest large seeds and acorns from broadleaved
trees, grey squirrels have a competitive advantage over red squirrels that
results in weight loss and reduced breeding success for reds.

Extensive tree
cutting between 1914 and 1945 throughout Britain, and subsequent felling of
Scots pine and Norway spruce plantations as they mature, have largely been
replaced with new plantations of Sitka spruce that offer a limited food supply
for red squirrels. Remaining woodlands have been further fragmented by the loss
of an estimated 50% of the hedgerow habitat in Scotland between the 1940s and
1980s. Continuity of habitat is important, and the loss of hedgerow links between
woodlands has resulted in the isolation of red squirrel populations, increasing
the risk of losses from predation when red squirrels have to cross open areas.

But the most
devastating reason for the decline of red squirrels has been the incursion of
the Squirrelpox virus, carried by gray squirrels. Harmless to them, it’s lethal
to the native reds, with the reds dying a horrible death over two weeks. The
Squirrelpox virus also has the devastating effect of speeding up the rate at
which grey squirrels displace and replace reds (usually about 15 years) by a
factor of twenty, denying researchers adequate time to develop an effective
vaccine for reds.

Scotland is
home to over 75% of Britain’s endangered red squirrels with the country
representing one of the last strongholds for the species in the UK. We saw
numerous red squirrel road-crossing signs throughout Scotland, and a very
concerted effort has been undertaken to vastly reduce the grey squirrel
population.

Scotland’s red
squirrel is a bit different than Wisconsin’s, most notably in having pointed
ear tufts, but otherwise looks and acts the same. How interesting that a
species that is considered so common to us is of such great concern to people
in Britain.

Other Invasive North American Species - Mink and Ruddy Duck

Ruddy
ducks became established in Britain and Europe after escaping from wildfowl
collections. In Spain, ruddies hybridize with an endangered species of
white-headed ducks, but because ruddies are a dominating species, the fear is
that they will exterminate the white-headed duck from all of Western Europe. Thus,
a major cull of ruddy ducks is currently being carried out by many countries
across Europe.

As
for American minks, Scotland has been overrun by them. The animals were brought
to Britain back in the 1950s to be farmed for fur coats, and now tens of
thousands are running wild and wreaking havoc on other species.

The minks
patrol river and loch banks looking for birds and frogs and small mammals — in
particular voles. Voles are beloved in Scotland, famed by Scottish novelist
Kenneth Grahame who used a water vole as a main character in his children's
book TheWind in the Willows.

Now, 95% of
the voles are gone, thanks in large part to the minks. The Scots have
a major campaign to clear their lands of the invaders, with the goal to kill
them all! So far, nearly 4,000 square miles of Scotland have been declared
mink-free.

Osprey Reestablishment

And
then there are those species that are circumpolar in their distribution, some
of which are doing very well here, but are struggling there. Ospreys are
particularly notable. The osprey used to be
distributed throughout Europe, but heavy persecution, mainly by Victorian egg
and skin collectors during the 19th and early 20th century, brought about dramatic
decreases and extinctions.

The osprey
became extinct as a breeding bird in England in 1840 and in Scotland in 1916.
In 1954, it recolonized naturally and a pair has nested successfully almost
every year since 1959 at Loch Garten, an RSPB reserve in Scotland’s Cairngorms
National Park. The Osprey Centre at Loch Garten has become one of the most
famous conservation sites in the world –
over 2 million people have visited to see a particularly famous pair of nesting
ospreys, the 27-year-old female of which has now returned for 22 consecutive
years to breed, and has successfully reared 50 chicks. She winters
roughly 6,000 miles south in West Africa.

The osprey’s
overall reestablishment was very slow, probably because of organochlorine
pesticides in the food chain and due to the continued activities of egg
collectors, and had reached only 14 pairs by 1976. However, by 2001, 158
breeding pairs were located, mainly in Scotland. That same year saw the first
successful nesting of ospreys in England.

Ospreys now number around 200 pairs in Scotland,
and we saw one nest on top of an electric pole, just like around here, on a
trail at the Pass of Killiecrankie not too far from Loch Garten.

Handa Island Seabirds

Perhaps
the birding highlight of our trip was a visit to Handa Island nature reserve near
the tip of northwestern Scotland. Managed by the
Scottish Wildlife Trust (SWT) Handa’s dramatic sea cliffs host one of the
largest seabird breeding colonies in Europe with around 100,000 breeding birds,
including internationally important numbers of guillemots and razorbills.

From the cliff
path, we could observe the nesting bird's daily activities. Around 45,000
guillemots nest precariously on narrow cliff ledges, along with thousands of
kittiwakes, fulmars, razorbills, and a small number of puffins that breed in
burrows lining the cliff edges.

Great skuas
and Arctic skuas nested on the ground across the moorland areas of the island, along
with red grouse and common snipe on the island, all of which were remarkably
approachable because of no hunting on the island. We were able to watch a red
grouse displaying for a female who paid him little attention, instead
continually bathing herself in dirt. Arctic tern colonies have also recently
formed on the southern shores and we could see them feeding in the shallows of
the landing beach.

Back in the U.S. – Great Backyard Bird
Count

Participation
in the 15th Great Backyard Bird Count, February 17-20, shattered all previous
records. Bird watchers in the U.S. and Canada submitted more than 104,000
checklists, reported 623 species, and observed more than 17.4 million birds.
New checklist records were set in 22 states and in 6 Canadian provinces.

Participants reported the northern cardinal
on more checklists than any other species for the eighth year in a row, closely
followed by the mourning dove. The most numerous bird species reported during
this year’s count was the snow goose, followed by the tree swallow, with its
first-ever top-10 appearance. A single massive flock of an estimated one
million tree swallows was reported in Ruskin, Florida (Google this event to see videos)!

This year’s
GBBC results are available on the website (http://www.birdsource.org/gbbc/).
GBBC maps show reports for snowy owls that plainly demonstrate the massive
influx compared to previous years. The maps also show that common redpolls moved
farther south in western areas in search of food, while a lack of acorns may have
reduced reported numbers of blue jays in the Northeast. Sandhill cranes and
red-winged blackbirds were also found to be already migrating during the count.